Traditional user interface hardware systems such as tactile keyboards typically are actuated by applying pressure to a selected key, which then causes the actuation of further components within the keypad or keyboard. The key to which such pressure is applied generally is a discrete hardware element, and the key can readily be designed to require the application of a pressure exceeding a threshold level for its actuation. As a result, the discrete hardware keys in such systems foster accurate data entry at high speeds. One major disadvantage of such hardware systems, however, is that the keyboard layouts are either permanent, or are cumbersome and expensive to reconfigure. Hence, these systems generally are standardized and not tailored to individual users. Moreover, separate systems must be designed and produced for use in different applications.
Computer-based systems have long dominated efforts to resolve the shortcomings of such traditional hardware systems. User-centered tailoring of the hardware and software of a computer system to the functional requirements of the market and industry it is designed for has been shown to improve operator performance and operational effectiveness.
In particular, touch screens have been widely adopted as replacements for traditional user interface hardware such as mechanically-actuated keypads or keyboards, because of their ease and versatility of operation. A user interface system having a touch screen display can, for example, be programmed so that the screen displays graphic objects to facilitate data entry. Such graphic objects can include, for example, menus, collections of icons, and representations of characters, numerals, buttons, tabs and the like. An operator enters data into such a user interface system by touching the screen in appropriate locations as suggested by the graphic objects. The screen senses the touch, and the grid position of the touch on the screen. The user interface system interprets the touch in accordance with its programming and registers the data indicated by the touch. Touch screen systems can easily be reprogrammed with any desired array of graphic objects tailored to the needs of the application and the operator. Such reprogramming is rapid and inexpensive, as it is implemented in software with no requirement for costly hardware design changes.
Touch screens are used in a wide variety of applications. One common application is point-of-sale (POS) display screens used in retail sales. Another application is in master controls for industrial machinery, which can operate, for example, an entire factory, refinery, or warehouse. Where accuracy is critical, operation of a touch screen by direct manipulation can generate an unacceptable risk of errors. The graphic objects displayed on a touch screen are implemented together on a unitary, approximately flat surface. Hence, the accuracy with which a user touches a location with the requisite contact pressure required to actuate one selected graphic object out of many displayed on the same touch screen cannot be controlled by the touch screen itself. As a result, a finger carelessly applied to a portion of the touch screen adjacent to an intended portion selected, can result in erroneous data entry, double data entry, or in data non-entry. In addition, where an operator is handicapped, or has the task of operating a touch screen over an extended time period, direct manipulation can lead to errors caused by fatigue, impatience, inattentiveness and other human factors. These problems also lead to slow data input speeds, as the typical operator attempts to exercise care to minimize errors. Accordingly, there is a need for reconfigurable touch screen—based user interface systems that can be operated and reprogrammed with improved accuracy and ease of use.